It was established by Claudius Ptolemy. In Japan, it can be seen in the northern sky around sunset in autumn. It is constellation that represents Queen Cassiopeia tied to a chair. When the Ethiopian royal family was ruled by King Cepheus and Queen Cassiopeia, Cassiopeia, who was very beautiful and had a strong sense of pride, said, "Even the daughters of the sea god cannot compare to my beauty." Hearing this, Poseidon, the god of the sea, became furious. He sent a giant whale living in the sea to Ethiopia, causing a tsunami. To put an end to this disaster, Cassiopeia and Cepheus sacrificed their daughter Andromeda as ordered.